This invention relates to valves and more particularly, to an oscillating valve or air relay suitable for use in operating chemical injectors and the like. A typical oscillating valve and its use with a chemical injector is shown in U.S. Pat. No. 3,387,563. In operation, a continuous supply of air or other gas under pressure is connected to the supply port of the valve, and a piston pump or other load is connected to the drive port. The oscillating valve functions automatically to periodically provide air under pressure at the drive port for actuating the load. The timing of the oscillatory action of the valve is adjustable, as by varying the orifice of a needle valve in a flow path between the drive port and a chamber within the valve.
The typical oscillating valve of the prior art uses one or more diaphragms and one or more springs to achieve the oscillatory action. Also, the supply pressure at which the prior art valves can operate is limited to about 65 psi. When it is desired to operate the load at a higher pressure, two valves have been operated in sequence.
It is an object of the present invention to provide a new and improved oscillating valve or air relay which does not require diaphragms or springs. It is another object of the invention to provide such a new and improved valve which can be operated at higher supply pressures, such as 200 psi. A further object of the invention is to provide such a valve which can be utilized in combination with an external accumulator to provide a wider range of operating frequencies. These and other objects, advantages, features and results will more fully appear in the course of the following description.